I've heard Seattle traffic can be really bad. How much time should I allow to drive from downtown to and from the airport?

Arriving Seattle 10pm (Friday)
Leaving Seattle 5pm (Saturday)

Thanks!

My guess is that the 10 p.m. flight into Seatac won't be a problem - 20 minutes to downtown on I-5?

Leaving Seatac at 5 p.m. on a Saturday means you probably should be there at 3 (although midafternoon security lines likely not long) - depending on what is going on in the area that Saturday (at Qwest or Safeco Fields for instance), it could easily take longer to drive to Seatac than the 20 minutes - could be quicker in the HOV lane if there is more than one in the car.

True enough what you have heard, but you should be OK at 10 o'clock at night! The drive takes ~25 mins. Maybe allow a little extra in case there's a jamb up on I-5 Saturday afternoon, like 45 mins. just to be safe?

Yes, I figured the 10:00 flight wouldn't be a problem. We are flying back at 6:05 so I figured I need to be to the airport by 5 on Saturday at least. I know from living in Southern California there were days it took me one hour to get to LAX and other days 3 hours. I didn't know if Seattle is as bad as the 405 freeway that time of day.

If I leave at 3:00 on Saturday to catch a 6:05 flight would that be about right?